Ink jet printing systems have been employed utilizing intermediate transfer surfaces, such as that disclosed in U.S. Pat. No. 4,538,156 to Durkee et al. This patent discloses a system wherein an intermediate transfer drum is employed with a printhead. A final receiving surface of paper is brought into contact with the intermediate transfer drum after the image has been placed thereon by the nozzles in the printhead. The image is then transferred to the final receiving surface.
U.S. Pat. No. 5,099,256 to Anderson describes an intermediate drum with a surface which receives ink droplets from a printhead. The intermediate drum surface is thermally conductive and formed from a suitable film-forming silicone polymer allegedly having a high surface energy and high degree of surface roughness to prevent movement of the ink droplets after receipt from the printhead nozzles. Other imaging patents, such as U.S. Pat. Nos. 4,731,647 and 4,833,530 to Kohsahi, disclose a solvent which is deposited on colorant to dissolve the colorant and form a transferable drop to a recording medium. The colorants are deposited directly onto paper or plastic colorant transfer sheets. The transferable drops are then contact transferred to the final receiving surface medium, such as paper.
U.S. Pat. No. 4,673,303 to Sansone et al. discloses an offset ink jet postage printing method and apparatus in which an inking roll applies ink to the first region of a dye plate. A lubricating hydrophilic oil can be applied to the exterior surface of the printing drum or roll to facilitate the accurate transfer of the images from the drum or roll to the receiving surface.
All of these processes do not achieve a complete image transfer from the intermediate transfer surface and, therefore, require a separate cleaning step to remove any residual ink from the intermediate receiving surface. The inclusion of cleaning apparatus is both costly and time consuming in color printing equipment. Prior intermediate transfer surfaces also have not been renewable.
Also, all of these prior processes are limited in the degree of image quality which can be achieved on different types of final receiving surfaces or print media. Since the inks are fluids, they are subject to uncontrolled bleeding on porous media, such as paper, and uncontrolled spreading on transparency films or glossy coated papers.
These problems are solved in the process and apparatus of the present invention by providing an apparatus and process which supplies a liquid layer as the intermediate transfer surface on a supporting surface for the transferred image. The image is then transferred with at least a portion of the liquid layer from the liquid layer to a final receiving medium. The image is preferably formed from a phase change ink. The apparatus and process produce uniformly high quality images on a wide range of media through the use of phase change ink that is transferred to the final receiving substrate or medium in a malleable solid state.